Interval, means how often the system checks for data.Samples, means how many data points are averaged on a rolling basis.Qos Interval, means how often the qos data actually gets written to the database.

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In this example, Interval is 5 minutes, Samples is 5, and QoS interval is 2. Data is written every 10 minutes (Interval x QoS Interval) into the database. ----------------------------------------

"Samples" affects the averaging applied to the measurements used to compare against thresholds. So in your example, you have samples set to 3, interval set to 5 and QOS interval set to 1. Then if your measures were 90 @ 5 minutes, 95 @ 10 minutes and​​ 100 @ 15 minutes, you have 3 QOS values sent at that point with values 90, 95, and 100. By the default settings, ​after you have "samples" number of samples, the probe will start comparing with the thresholds and that first comparison will be (90+95+100)/3 or 95%. If at 20 minutes you have another 100% QOS your next comparison will be (95+100+100)/3 or 98.3%. And if you are still at 100% at 25 minutes in, your next comparison would be (100+100+100)/3 or 100%.